Field of the Invention
The present invention relates to a pedestrian protection system for a vehicle having at least one impact-detecting sensor and a deformation element, which are arranged between a crossmember and a bumper cover of the vehicle, and having a control unit which analyzes the signals of the at least one sensor.
Description of the Background Art
A pedestrian protection system is disclosed in DE 10 2004 009 301 A1, which corresponds to US2007179693, and in DE 103 60 138 A1.
In the embodiment disclosed in DE 10 2004 009 301 A1, a bumper cover is arranged in front of a foam and a crossmember of the vehicle. Acceleration sensors are attached to the bumper cover between the bumper cover and foam and/or the crossmember. The signals from the acceleration sensors are evaluated in a control unit. In the case of an impact between a pedestrian and the vehicle, pedestrian protection functions such as an external airbag, for example, are triggered to lessen the consequences of the accident for the pedestrian.
The installation location for the acceleration sensors behind the bumper cover is to be regarded as an essential feature of said prior-art pedestrian protection system. Because of this location, the acceleration sensors are mounted close to a possible point of impact by the pedestrian, so that their signal strengths increase considerably in the case of a pedestrian accident and reliable detection of the acceleration signals is possible.
In the embodiment disclosed in DE 103 60 138 A1, a bumper cover is arranged in front of a foam and a crossmember of the vehicle. Piezoelectric collision-detecting sensors are arranged between the crossmember and the foam. In the case of an impact of a pedestrian with the bumper cover, the pressure is transmitted via the foam to the piezoelectric collision detection sensors and generates an electrical voltage, which can be evaluated as a signal. A control unit controls pedestrian protection functions depending on said signal.
The use of piezoelectric collision-detecting sensors are to be regarded as an essential feature of this prior-art pedestrian protection system. Voltages, which arise, for example, due to prior damage to the sensor pickup surfaces and could negatively impact the collision detection, can be reduced in these sensors.
The aforementioned embodiments require foam behind the bumper cover as a deformation element, in order to lessen the impact of the pedestrian, or as a force-transmitting element to transmit the force of the impact to the sensors. A sufficiently large foam volume is needed to achieve these actions.